Soybeans (i.e., seeds of Glycine max) are recognized to be an important oilseed crop in many parts of the world. For instance, approximately 65 to 75 million acres of soybeans are planted annually in the United States. Heterosis or hybrid vigor now advantageously can be used to increase the desired soybean yield in view of recent progress in this area.
Early work with respect to hybrid soybean production is disclosed in U.S. Pat. Nos. 3,903,645 and 4,077,157 to Bradner. These approaches have not become a commercial reality.
In commonly assigned U.S. Pat. Nos. 4,545,146 and 4,648,204 to Davis are disclosed novel routes to hybrid soybean production employing cytoplasmic male sterility and pollen transport by insects. These approaches are believed to provide a means for making hybrid soybeans a reality for farmers. However, when practicing such hybrid soybean production routes it previously has been considered to be important that the cytoplasmically male sterile plants and restorer male fertile plants be grown in adjacent strips in substantially uniform populations, and the resulting seeds harvested separately if one is to obtain the seeds capable of growing F.sub.1 hybrid soybean plants in a substantially pure form. In many states of the United States it is essential that the soybean seeds be of at least 95 percent purity if they are to be labelled a hybrid when marketed. Such split planting and selective harvesting significantly adds to the cost of the hybrid soybean production and inherently carries with it the potential for harmful error during either or both of these operations or during subsequent seed handling. It is also important for the soybean grower to be provided with F.sub.1 hybrid soybean planting seed which upon self-pollination will make possible a uniform harvest wherein substantially all of the resulting F.sub.2 seeds will possess the usual light-colored seedcoat so that the harvest will qualify for the highest available soybean grade.
In U.S. Pat. No. 3,842,538 to Barabas is discussed a method involving cytoplasmic male sterility and wind pollination for forming dissimilar F.sub.1 hybrid seed-grains on monocotyledons (i.e., cereals such as wheat) in which a color marker is placed in the seed pericarp of one of the parents (preferably the male), and the parent plants are planted in bulk. The seed pericarp there discussed is not maternal tissue and is non-analogous to the maternally-derived seedcoat which exists in a pod-forming legume crop such as soybeans. There is no discussion of the genetics involved in the Barabas process or how one could come into possession of the unusual crimson pericarp marker there discussed. If the crimson pericarp was dominantly transmitted (which may be likely) and present on the male parent, the process would be inoperative since all of the resulting offspring would possess a crimson pericarp and could not be separated on the basis of color. If the crimson pericarp was recessively transmitted and present on the male parent, any seeds produced by the grower upon self-pollination of the plants resulting from the growing of the F.sub.1 hybrid seed would segregate as to color thereby significantly lowering the grade of the seed-grain harvest. Also, the seed-grain (e.g., wheat) formed on the male parent of Barabas would tend to be less than pure because of the unreliability of the wind pollination involved in its formation and would tend to be discarded or scraped as stated at the bottom of Col. 1.
In commonly assigned copending U.S. Ser. No. 001,227, filed Jan. 6, 1987, to Calub is disclosed a specifically defined process for producing hybrid rice using cytoplasmic male sterility, bulk planting, and seed separation on the basis of seed hull color (as described).
It is an object of the present invention to provide an improved process for simultaneously forming in the same planting area (1) seeds capable of growing F.sub.1 hybrid Glycine max plants, and (2) seeds capable of growing restorer plants for the same.
It is an object of the present invention to provide an improved process for forming seeds capable of growing F.sub.1 hybrid Glycine max plants wherein a substantially random population of cytoplasmically male sterile and restorer parent soybean plants is grown in a planting area and pollen transfer is accomplished with the aid of pollen-carrying bees.
It is an object of the present invention to provide an improved process for the production of substantially uniform assemblages of (1) seeds capable of growing male fertile F.sub.1 hybrid Glycine max plants, and (2) seeds capable of growing restorer plants for use in the production of the same.
It is an object of the present invention to provide an improved hybrid soybean production process wherein the F.sub.1 hybrid soybean plants resulting from the planting of the seeds capable of forming the same upon self-pollination form seeds which substantially uniformly exhibit maternally-derived light-colored seedcoats in the F.sub.2 generation thereby enabling the grower to produce a substantially uniform soybean harvest.
It is another object of the present invention to provide an improved process for the formation of seeds capable of growing F.sub.1 hybrid Glycine max plants involving cytoplasmic male sterility wherein the costly strip planting of the parent plants is avoided and the parent plants are randomly grown in the same planting area.
It is a further object of the present invention to provide an improved process for the formation of seeds capable of growing F.sub.1 hybrid Glycine max plants wherein seeds formed on each of the parent plants simultaneously can be harvested in bulk and subsequently separated with accuracy.
It is yet another object of the present invention to provide an improved process for the formation of seeds capable of growing hybrid F.sub.1 hybrid Glycine max plants wherein the tedious selective harvesting of seeds formed on alternating strips of plants is avoided and the plants are grown in a configuration wherein pollen transfer by pollen-carrying bees readily is accomplished.
These and other objects as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.